Machine with mechanisms placed in displaceable boxes for the manufacturing and delivery of plastic bags of different lengths starting from a tubular sheet

ABSTRACT

A machine for manufacturing of plastic bags from a tubular web having a plurality of mechanisms for performing the various necessary operations, such as feeding the tubular web from a roll into the machine, thermowelding the web for forming bag portions, cooling the weldments with provisions for preventing deformations of the welded web, inserting a straw into the tubular web at each bag portion, cutting the finished bag portions off the tubular web and delivering the finished bags, whereby each one of the operating mechanisms is enclosed in a box and whereby some of the boxes are manually displaceable for varying the length of the bag portions.

United States Patent [72] Inventor Guido D. Bertoglio Lnpno-Viganello,Switzerland [2|] Appl. No. 831,192

[22] Filed- June 6, I969 [45] Patented Aug. 3, I971 [73] Assignee CentrnAnstalt Vndox, Liechtenstein [32] Priority Oct. 30, I968 [33]Switzerland Primary ExaminerTheron E. Condon Assistant Examiner-E. F.Desmond Attorney-Sparrow and Sparrow ABSTRACT: A machine formanufacturing of plastic bags from a tubular web having a pluralityof'mechanisms for performing the various necessary operations, such asfeeding the tubular web from a roll into the machine, thermowelding theweb for forming bag portions, cooling the weldments with provisions forpreventing deformations of the welded web, inserting a straw into thetubular web at each bag portion, cutting the finished bag portions offthe tubular web and delivering the finished bags, whereby each one ofthe operating mechanisms is enclosed in a box and whereby some of theboxes are manually displaceable for varying the length of the bagportions.

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SHEET 7 0F 9 gill/11111110001043 INVENTOR G i gmpiogko BY Q2wvou EMAearrau ATTORNEY h/llAiCliilNE WITH MECHANISMS PLACED ENDISPLACIEAELEMGXW son THE MANUFACTURING AND DELIVERY f" PLASHIG EAGS GilGIEFIFIEEUENT lbhhlG'i'liih Fi'i'AhTllhlG MGM A TiUiiiUlLdhmSli'iiEiE'lf The present invention relates to a machine formanufacturing and delivering plastic bags of different lengths startingfrom a tubular sheet and comprising:

means for introducing in the machine the flattened tubular sheet;

at least a pair of jaws for thermowelding the tubular sheet;

at least a pair of cooling jaws for the thermowelded portions;

a pair of endless conveying belts provided with transmission rollers andadapted to accompany the tubular sheet during its travel from thethermowelding jaws to the cooling jaws in such a manner that thethermowelded, hot and therefore deformable portions of said sheet areprevented from undergoing deformations;

transmission means;

mechanisms for introducing a straw into the tubular sheet at each bagsection;

means for cutting the bags away from the tubular sheet.

Said machine ischaracterized in that the mechanism controlling: themeans introducing the tubular sheet, the thermowelding jaws, the coolingjaws, the conveying means, the transmission means, the mechanism forintroducing thestraw and the cutting 'or separating means are located injust as many separated boxes spaceable at different distances withrespect to each other during the functioning of the machine in order toobtain bags of different lengths and furthermore in that said cuttingmeans are disposed at the end of the travel of the tubular sheet, sothat each bag may be separated from said tubular sheet when the bag isalready finished, with the straw already introduced therein.

To make the invention better understood a preferred and nonlimitativeembodiment thereof will be described hereinafter by way of example onlyand with reference to the accompanying drawings, in which:

FIG. i is a diagrammatic front view of the machine of the invention;

FIG. 2 is a plan view of same;

FIG. Zi'is a lateral diagrammatic view of the members transmitting themotion from the motor shaft to the grooved shafts actuating themechanisms of the various displaceable boxes;

FIG. d is a partial longitudinal sectional view talten along the planepassing through d-d of FIG. 2, wherein the members of FIG. 3 are shownin a position successively reached during the working;

FIG. 5 is a partial cross-sectional view through the machine of FIG. Itaken along a plane passing through 5-5 i.e. through the rollersprovided for the introduction of the tubular sheet;

FIG. 6 is a further partial cross-sectional view of the machine of FIG.i taken along the plane passing through 6-6 i.e. through the rollersactuating the pairs of endless conveying belts;

FIG. '7 is a partial cross-sectional view of the machine of FIG. I takenalong the plane passing through '7-7 i.e. through the box containing thethermowelding jaws for the tubular sheet;

FIG. h is a horizontal sectional view taken along the plane passingthrough h-h of FIG. 7;

FIG. 9 is a front view of the said thermowelding jaws;

FIG. id is the diagrammatic cross-sectional view of the cooling devicefor the thermowelding jaws at rest and a safety device which preventsthe interposed endless conveying belt made of heabresistant materialfrom being damaged when the jaws are closed;

FIG. ill. is a front view of the thermowelding box showing the detailsof said safety device;

FIG. I2 is a bash view on the thermowelding box showing a pair ofelectromagnets controlling said safety device;

FIG. I3 is a diagrammatic front view of the box containing thetransmission members i.e. the means feeding the tubular sheet where thislast leaves the conveying belts to be taken up by further transportmeans and finally reaches the cutting means;

FIGS. M and R5 are partial plan views of the members located at the endof the travel of the tubular sheet;

FIG. 16 is the cross section through the box comprising the feedingmembers i.e. a section taken along the plane 16-416 in FIG. ll and inFIG. I3;

HG. 117 is the cross-sectional view of the same box but talten along theplane passing through 37-47 of HG. i;

FIG. i8 is the cross section of the box containing the membersintroducing the straw in each bag i.e. the section taken along thevertical plane passing through lt5lh in FIG. 1;

FIG. i9 is a detail view of the hopper containing the straws;

FlG. is the cross section taken along the plane passing through 2-2tl inFIG. I i.e. through the box comprising the cutting means;

FIG. 21 isa cross section of FIG. 2d taken along a plane passing through21-21 to show the members blocking the tubular sheet to allow for thecutting;

FIG. 22 is a section of FIG. 20 taken along the plane passing through22-22 i.e. through the lever controlling the cutting operation.

With reference to FIG. l: the machine of the invention comprises theframe l supporting the bobbin 2 having wound thereon the flattenedtubular sheet which will be used for manufacturing the bags. Saidtubular sheet is made to pass between the guide means 3 and successivelythrough the introductory members of the box and, finally, through thevarious groups of the following members contained in just as many boxes:lfi--I1l-l.2l3l-I4l.

The box w comprises the members performing the thermowelding of thetubular sheet to form the bottom of each bag. The box ill comprises themembers adapted to operate the cooling of the thermowelded and still hotportions of the bag so as to prevent the deformation thereof.

The box I2 contains the transmission members for the endless belts whichserve to feed the thermoweldcd and cooled tubular sheet to thesuccessive groups of members constituting the boxes l2 and Id.

The box 13 contains the members adapted to introduce the straw into eachbag while still attached to the tubular sheet.

The box id contains the members operating the crosscutting of thetubular sheet at the opening side of each bag as .well as delivering thefinished and cut bag to the (nonrepresented) machine that will take itup for automatically filling and closing it.

The basic characteristic of the machine according to the presentinvention consists in that the groups of members form ing a part of theboxes indicated with i9iil-li-I2-i3- Id are displaceable at variablemutual distances and may be fined in the desired position to permit themanufacturing of bags of different lengths.

A second basic characteristic directly depending from the first oneconsists in that the'bags are not cut right away from the tubular sheetat the moment they enter the box 9 but only at the end of the travel ofsaid tubular sheet i.e. when they enter the box lid so that theymaintain their perfect reciprocal disposition and rigidity up to theirdelivery to the filling machine.

The machine according to the present invention differs thereforeconsiderably from the conventional machines in which bags of differentlengths are obtained by varying the speed of introduction of the tubularsheet and by cutting each bagat the very moment the tubular sheet isintroduced in the machine i.e. before the thermowelding has beeneffected.

In said conventional machines, contrarily to what is done according tothe present invention, the cutting members, the thermowelding means, thecooling means, the means for introducing the straw and the deliverymeans maintain unchanged their reciprocal position.

In the following there will be described the basic members of themachine of the invention.

First of all it should be pointed out that the mutual displace-- ment ofthe various boxes to have the machine produce bags of different lengthsis obtained, for each box, by means of a gear 15 (see FIGS. 1 and'7)engaging a rack 27 which extends throughout the whole length of themachine and is fixed to the frame 1.

The rotation of the gear 15 is effected by introducing a wrench at theend of the shaft 29 (FIGQ'I) having a square cross section.

Each box is fixed again by means of an eccentric means 30 (FIGS. 1 andcoaxial to the shaft 23 (FIG. 10) similar to the preceding one andadapted to be rotated by a similar wrench. Some boxes, such'as box 9 and12, may also stay stationary since the variation of the reciprocaldistance between the various boxes may be obtained even if some of themare stationary. Of course these stationary boxes will be provided withno gear or eccentric means 30.

There will be now described the means transmitting the motion from thedrive shaft 24 (FIGS. 1 and 2) to the mechanisms contained in thevarious boxes 9l011l2 13-14'.

These members comprise essentially three splined shafts 31, 32, 33(FIGS. 1 and 2), two of which and namely shafts 31 and 32 receive arotary and uniform motion while the third one 33 is subjected tointermittent rotary motion to control the intermittent feedingdisplacements of the tubular sheet. To this scope, as it is shown inFIGS. 3 and 4, the uniform rotary motion is transmitted from the driveshaft 24 to the toothed .wheel 34, to the chain 35 to the toothed wheel36 coaxial tothe grooved shaft 31 and to the pair of transmission gears37 and Mac as to actuate in a uniform manner the two splined shafts 31and 32. The first shaft 31 is intended to operate the cams which, in theboxes 10 and 11 (FIGS. 1 and 2), are responsible foropening and closingthe thennowelding and cooling jaws while the second shaft 32 is adaptedto control the cutting members and the means for introducing the straw,all of them being contained in the boxes 13 and 14-.

The third splined shaft intermittently operating, in the box 9, therollers 39-40 introducing the tubular sheet (FIG. I) and, in the box 12,the transmission drum 42 feeding the tubular sheet as well as the pairof conveying belts 43, 44 (FIG. I) receives its intermittent motion fromthe drive shaft 24 (FIGS. 3-4) over a flywheel 45, the eccentric 46, theconnecting rod 47 and the rack 48 engaging a toothed portion at theperiphery of the end of said shaft 33. This mechanism is also known as arack-and-pinion slider crank motion whereby the pinion (in this case theshaft 33) has a conventional overrunning clutch (not shown in thedrawing), 80 that the shaft is not rotated during the return stroke ofthe rack. The amplitude of the intermittent motion i.e. the length ofthe intermittent travel 'of the tubular sheet which corresponds to thelength of each bag is adjustable by varying the position of the pivot 46in the radial groove 49 of the flywheel 45.

There will now be described the members making up the various boxes.Besides the introductory rollers 39, 40 shown in FIG. 1 and bettervisible in FIG. 5 which have the intermittent motion imparted thereto bythe splined shaft 33 over the endless screw 50 and the two complementarywheels 51, 52, the box 9 also contains the two drums 53-54 (FIG. 6)which have the two heat-resistant belts 43, 44 of carbon tetrafluorideor any other suitable synthetic resin wound thereon as shown in FIG. 1.

Actuation of the two drums 53,54 also by the shaft 33 takes place overthe endless screw and the two complementary wheels 55, S6..The handwhecl57 (FIG. 6) serves to initially introduce by hand the tubular sheet 2(FIG. 1).

FIG. 7 shows the members contained in the box 10. They comprise the cam58 angularly fixed to its splined drive shaft 31, but axially slidablewith respectto same over the longitudinal splines or grooves 31' (FIG.8) of said shaft 31 so as to allow for the displacement of the box 10.

Said cam 58 controls the rollers 59, 60 (FIG. 7) acting as tappet meansand carried by the arms 61, 62 pivoted *n 63, 64, said arms supportingthe thermowelding jaws 65, 66.

Throughxopera'tion of the arms 61,62 the jaws 65, 66 are closed and.openeds During the closing of same the tubular sheet 2 is thermoweldedat the bottom of each bag since the temperature of the jaws is broughtby means of electrical resistance to a value corresponding to thethermowelding temperature of the thermoplastic material making up thetubular sheet 2. To prevent the jaws from sticking to the tubular sheet2, the sheet and the jaws will have two strips 43, 44 of carbontetrafluoride or similar resin (see also FIG. I) interposed therebetweenand wound in a closed circle about the drums 53, 54and the rollc'rs 66,68, 69, 70 which are mutually displaceable to adjust the tension of thestrips so as to constitute two endless conveying means movable in thedirectionof the arrows 71, 72. Beside preventing the adhering orsticking of the thermowelding jaws to the tubular sheet said strips alsohave the main task of accompanying the th ermowelded and hot portion ofthe tubular sheet 2 up to the cooling jaw contained in box 11.

In FIG. 7 there are indicated pressure adjusting means 73, pressuresprings 74, connections 175 for the circulation of a fluid for coolingthe supports of the thermowelding jaws and the protection arms 75, 76,77, 78 illustrated in FIG. 11. These arms are provided for protectingthe elastic strips 43, 44 from the thermal radiation of thethermowelding jaws when same are open (FIG. 10). Said protection armsare actuated by electromagnetic pistons 79, 80 (FIGS. 16, 12) which keepsaid arms open as indicated with dash line in FIG. I! when the jaws. 65,66 effect the thermowelding operation and close them when the jaws openagain.

Should the-electromagnetic pistons 79, 80 fail to work a mechanicalsystem of levers 81 (FIG. 11) receiving the movement from the memberscontrolling the opening of the jaws 65, 66 will provide for the closingof the arms 75, 76, 77 78 as illustrated in FIG. 11. I

The cooling jaws in box 11 (FIG. 1) are quite similar to thethermowelding jaws in box 10 except that they are cooled by a coolingliquid instead of being thermoheated and that they do not have anyprotection jaws. Therefore they will not be described any further. I

The transmission members of the box 12 comprise, as illustrated in FIG.13, the transmission rollers 67, 68 for the conveying plastic strip.43,the transmission rollers 68, '70 for the conveying plastic strip 44 andthe drum 42 (see also FIG. 16) which is provided with grooves adapted toreceive just as many thin belts 83 (FIGS. 13 and l) forming, as a whole,an elastic carpet adapted to receive the tubular sheet 2 moving thereonas it comes from the conveying strips 43, 44. The motion is imparted tothe drum 42 by the splined shaft 33 (FIGS. 1, 16) over the twocomplementary wheels 85, 86 (FIG. 16).

The pulley 84 connected to the shaft of the wheel or gear 85 is adaptedto receive a (nonrepresented) belt leading from a pulley 200 at the endof a cross-shaft 201 (P16. 20) imparting a supplementary motion to thepair of rollers 116, 117 (FIG. 1) feeding the tubular sheet 2 on thebelt carpet 83.

The axes of rollers 67, 70 (see FIGS. 13 and 17) are displaceable withrespect to the ones of rollers 68, 69 to vary the tension of theconveying strips 43, 44 (FIG. 13). This is obtained by means of pivots87, 88 which are eccentric with respect to the blocking bushes 89, 90(see FIG. 17).

The members for introducing the straw 'into each bag and forming a partof box 13 (FIG. 1) comprise: a hopper 91 (FIG. 19) adapted to'receivethe straws 92 which, one by one, are made to fall by gravity through thepassage 93.

The bottom of the passage93 has a needle 94 (FIG. 18) placed thereon,said needle having its inner diameter corresponding to the outerdiameter of each straw. The needle is fixed to a slide member 97 slidingwithin two guides.

The arm 98 actuates the slide member 97 over a bar 114 which providesfor the introduction of the needle into the tubular sheet 2. v

Operation takes place as follows:

, The piston is initially displaced completely to the left. A straw 92-coming down from the hopper 91 may therefore enter into the needle 94 infront of the piston 95 driven by a cam. The lever 95 drives to the rightthe needle 94 together with the straw 92, thereby perforating thetubular sheet 2 which is opened by an air jet coming from a side of theneedle itself and blowing into a pocket portion suitable to receive thestraw. The needle penetrates into the tubular sheet up to aboutone-fourth of its length. The introduction is effected by the compressedair acting on the piston 95 and displacing same completely to the rightso that the straw penetrates into the pocket of the tubular sheet 2while the needle 94 stays stationary.

After this operation has taken place, a further air jet acts on thepiston 95 from the right to the left taking same back to its initialposition while the lever 98 takes the needle back to the positionsuitable to receive a further straw. The needle has therefore to: toperforate the tubular sheet, provide for the opening of the pocket,penetrate for about one-fourth of its length into the pocket and guidethe straw during its penetration into the said pocket.

FIG. 20 is a view of the cutting device in the box 14 (FIG. 1). Samecomprises the blade I00 carried by the slide 101 which is made to moveon the whole width of the tubular sheet 2 by the arm 102 actuated by thelink member 103 over the eccentric pivot 104 controlled by the flywheel105 which receives its motion from the splined shaft 32 (compare withFIG. 1).

At the moment of the cutting, the tubular sheet 2 is blocked by thepressure member 107 (FIG. 21) actuated by the tappet means 108 over thecam 109 actuated by the shaft 110 which alsoreceives the motion from thesplined shaft 32.

The grooved roller ill (see also FIG. 1) acts as transmission roller forthe belts 83 forming the supporting and conveying surface for thetubular sheet 2.

After having been cut, the bag is conveyed by the belts 83 up to a step112 (FIG. 1) which sets a limit for the travel of the tubular sheet.From here the bag is automatically taken up by the filling machine whichis not represented and the operations of which are synchronized withrespect to the main drive shaft 24.

lclaim:

1. A machine for the manufacturing and the delivery of plastic bags ofvarious lengths obtained from a flattened tubular sheet, said machinecomprising:

a. feeding means for leading said flattened tubular sheet into saidmachine b. at least one pair of jaws for thermowelding said tubularsheet,

c. at least one pair of cooling jaws for the thermowelded portions,

d. a pair of endless conveying belts provided with transmission rollersand disposed for accompanying said tubular sheet during the travelthereof from said thermowelding jaws to said cooling jaws for preventingsaid thermowelded deformable portions of said sheet from being deformed,

e. transmission means,

f. mechanisms for introducing straws into said tubular sheet at each bagsection,

g. means for cutting said bags, thereby separating said bags from eachother,

said machine being characterized by the mechanisms controlling saidmeans introducing said tubular sheet, said thermowelding jaws, saidcooling jaws, said conveying means, said transmission means, saidmechanisms for introducing said straw into said bag and said cutting;means being located in separate boxes spaceable at different distanceswith respect to each other even during the operation of said machine inorder to obtain bags of various lengths, and furthermore by said cuttingmeans being disposed at the end of the travel of said tubular sheet sothat each bag may be cutaway from said tubular sheet after it had beenfinished with said straw introduced therein.

- 2. The machine as claimed in claim 1, including gear means in certainof said boxes and a stationary rack, said gear means engaging said rack,said boxes being disposed to be displaced during the operation of saidmachine by rotation of said gear means and a plurality of eccentricmembers mounted on shafts, said eccentric members being actuated by saidshafts and being disposed for locking said boxes in place.

3. The machine as claimed in claim 1, and further comprising threesplined shafts and a main drive shaft, two first ones of said splinedshafts having gears, said main shaft driving said first two splinedshafts, a slider crank mechanism on said main shaft disposed to drivesaid third splined shaft, said slider crank mechanism having a rack andgear teeth cut on said third shaft for intermittently driving saidfeeding means and said conveying means by an amount corresponding to thelength of a bag; the amplitude of said intermittent motion beingcontrolled by varying the eccentricity of said slider crank.

4. The machine as claimed in claim 3, said slider crank mechanismcomprising a flywheel and said rack comprising a connecting rod and acrank knob, said] groove disposed for dis placeably receiving said crankknob.

5. The machine as claimed in claim ll comprising further a cam fixedrotatably on one of the two first splined shafts but axially slidingwith respect thereto by virtue of said splines, said cam located in thebox containing said thermowelding jaws, disposed for allowing for thedisplacement of said box, rollers operated by said cam and acting astappet means, said rollers carried by arms pivoted at one of their ends,said cam controlling said thermowelding jaws, strips of heat-resistingcarbon tetrafluoride being interposed between said ther mowelding jawsand said tubular sheet to be welded and protection amis pivoted at oneof their ends disposed for protecting said carbon tetrafluoride stripsfrom the thermal radiation of said thermowelding jaws in the openposition of the latter.

6. The machine as claimed in claim 5, further comprising electromagneticpistons, said pistons disposed for actuating said protection arms, saidpistons also disposed for maintaining said arms open while said jawsbeing open, and a mechanical lever system disposed for being actuated bysaid cam controlling the opening of said thermowelding jaws and theclosing said arms in the case of said electromagnetic pistons failing tooperate.

1. A machine for the manufacturing and the delivery of plastic bags ofvarious lengths obtained from a flattened tubular sheet, said machinecomprising: a. feeding means for leading said flattened tubular sheetinto said machine, b. at least one pair of jaws for thermowelding saidtubular sheet, c. at least one pair of cooling jaws for the thermoweldedportions, d. a pair of endless conveying belts provided withtransmission rollers and disposed for accompanying saiD tubular sheetduring the travel thereof from said thermowelding jaws to said coolingjaws for preventing said thermowelded deformable portions of said sheetfrom being deformed, e. transmission means, f. mechanisms forintroducing straws into said tubular sheet at each bag section, g. meansfor cutting said bags, thereby separating said bags from each other,said machine being characterized by the mechanisms controlling saidmeans introducing said tubular sheet, said thermowelding jaws, saidcooling jaws, said conveying means, said transmission means, saidmechanisms for introducing said straw into said bag and said cuttingmeans being located in separate boxes spaceable at different distanceswith respect to each other even during the operation of said machine inorder to obtain bags of various lengths, and furthermore by said cuttingmeans being disposed at the end of the travel of said tubular sheet sothat each bag may be cut away from said tubular sheet after it had beenfinished with said straw introduced therein.
 2. The machine as claimedin claim 1, including gear means in certain of said boxes and astationary rack, said gear means engaging said rack, said boxes beingdisposed to be displaced during the operation of said machine byrotation of said gear means and a plurality of eccentric members mountedon shafts, said eccentric members being actuated by said shafts andbeing disposed for locking said boxes in place.
 3. The machine asclaimed in claim 1, and further comprising three splined shafts and amain drive shaft, two first ones of said splined shafts having gears,said main shaft driving said first two splined shafts, a slider crankmechanism on said main shaft disposed to drive said third splined shaft,said slider crank mechanism having a rack and gear teeth cut on saidthird shaft for intermittently driving said feeding means and saidconveying means by an amount corresponding to the length of a bag; theamplitude of said intermittent motion being controlled by varying theeccentricity of said slider crank.
 4. The machine as claimed in claim 3,said slider crank mechanism comprising a flywheel and said rackcomprising a connecting rod and a crank knob, said groove disposed fordisplaceably receiving said crank knob.
 5. The machine as claimed inclaim 1 comprising further a cam fixed rotatably on one of the two firstsplined shafts but axially sliding with respect thereto by virtue ofsaid splines, said cam located in the box containing said thermoweldingjaws, disposed for allowing for the displacement of said box, rollersoperated by said cam and acting as tappet means, said rollers carried byarms pivoted at one of their ends, said cam controlling saidthermowelding jaws, strips of heat-resisting carbon tetrafluoride beinginterposed between said thermowelding jaws and said tubular sheet to bewelded and protection arms pivoted at one of their ends disposed forprotecting said carbon tetrafluoride strips from the thermal radiationof said thermowelding jaws in the open position of the latter.
 6. Themachine as claimed in claim 5, further comprising electromagneticpistons, said pistons disposed for actuating said protection arms, saidpistons also disposed for maintaining said arms open while said jawsbeing open, and a mechanical lever system disposed for being actuated bysaid cam controlling the opening of said thermowelding jaws and theclosing said arms in the case of said electromagnetic pistons failing tooperate.